Small modular reactors (SMRs) are at the forefront of new reactor designs worldwide due to their characteristics that meet the current demands from the global energy sector, combining flexibility for application with clean energy production. There are over a hundred SMR projects under development globally, utilizing different technologies. Brazil plans to use SMRs as part of its strategy to strengthen energy security and technological advancement, as foreseen in the National Energy Plan 2050 (PNE 2050). To monitor the development stage of SMR projects around the world, for which information is available in open literature, OECD/NEA created a metric based on six critical aspects influencing the implementation of these projects: licensing, location, financing, supply chain, engagement, and nuclear fuel. This paper presents the results of a bibliographic and documentary review focused on analyzing the possibilities of implementing SMRs in Brazil in order to assess the maturity level of each aspect for the implementation of this technology, adopting OECD/NEA criteria as a reference. The results revealed that, in Brazil, the six aspects evaluated show a certain degree of maturity, but there are important challenges to be faced in order to enable the implementation of SMR technology as part of the solutions to diversify the energy matrix in the coming years.
Water scarcity in the Brazilian semi-arid region makes desalination via reverse osmosis a strategic solution for rural community water supply. However, the interaction of groundwater with geological formations rich in uranium and thorium minerals can favor the natural occurrence of radionuclides, especially radium, in desalination systems. During operation, filtration membranes act as efficient physical barriers, retaining these radionuclides and, upon reaching the end of their service life, generating radiologically significant waste. This study evaluated the presence of the isotopes 226Ra and 228Ra in filtering elements from desalination systems installed in the municipality of Riacho das Almas, Pernambuco, Brazil, and the potential environmental and radiological impacts associated with them. Filters collected from seven wells were calcined and analyzed by gamma spectrometry. 226Ra activities ranged from 0.33 to 7.08 Bq/g, with two wells showing values above the 1 Bq/g limit established by the National Nuclear Energy Commission, and 228Ra was not detected. The results confirm the efficiency of membranes in Ra retention but highlight the need for specific protocols to safely manage and dispose of this waste and mitigate occupational and environmental risks.
The study of neutron behavior and interactions within the core of a nuclear reactor is essential for ensuring criticality control. The most accurate deterministic framework for modeling these phenomena is the Neutron Transport Equation, which, with the exception of stochastic methods such as Monte Carlo, is typically solved using fine-mesh numerical methods. However, such approaches often entail considerable computational costs to achieve high-fidelity results. In this work, we propose a numerical-analytical solution to the one-dimensional, monoenergetic neutron transport equation with isotropic scattering, formulated for eigenvalue problems and employing the discrete ordinates (SN) method. The proposed formulation is presented through a fully explicit and self-contained step-by-step derivation, emphasizing transparency and reproducibility of the numerical-analytical approach. To assess the accuracy and efficiency of the proposed approach, results were compared with those obtained from a purely numerical method developed in this study, as well as with benchmark solutions reported in the literature. In all cases, the proposed method exhibited excellent agreement with reference data, along with a significant reduction in computational time.
Hydrogen is an important energy vector for the global energy transition. Due to its low carbon emissions, it has become a central subject of study for major nations. Small modular nuclear reactors (SMRs) represent an innovative approach in the nuclear field. This technology provides greater versatility, safety, and lower costs for energy production on a reduced scale compared with large nuclear reactors (LRs). This paper presents an economic evaluation of hydrogen production using a Small Modular Nuclear Reactor (SMR) as the primary energy source. The methodology uses the Hydrogen Economic Evaluation Programme (HEEP) software provided by the International Atomic Energy Agency (IAEA) to estimate the levelized cost of hydrogen production (LCOH, in USD/kg of H2) using SMRs. The model considers intrinsic characteristics of the power generation plant and of the Polymer Electrolyte Membrane (PEM) plant, the latter supplied by Hytron/NEA. To validate the methodology, it was necessary to evaluate the hydrogen production costs for a large reactor on the market, the AP1000 from Westinghouse. Based on these results, a 77 MWe NuScale SMR built under the same inflationary conditions as the LR was evaluated to avoid significant distortions in the results. For a realistic evaluation, cost studies provided by international institutions such as MIT and the U.S. Department of Energy`s Nuclear Energy Administration (DOE/NEA), and, when possible, by NuScale and Westinghouse, the companies responsible for the reactors being analyzed, were used. Preliminary results show that SMRs present significant competitiveness in terms of levelized cost of hydrogen compared to alternative clean energy sources such as renewable, including solar photovoltaic, solar thermal, and wind power. Due to the versatile, scalable, continuous, predictable, and dispatchable generation profile of SMRs, the cost difference found is negligible. This validates the potential of nuclear technology, which plays a strategic role in the energy transition both globally and in Brazil, and reinforces the importance of in-depth assessments on the subject.
The TRIGA® (Training, Research, Isotope General Atomics) are reactors that, currently, are utilized for staff training, radioisotope production and for researching in many areas of science; nowadays, more than 20 countries own TRIGAs®, including Brazil. These reactors have two operating modes: steady state (where it operates within constant neutron flux and its parameters also remain constant) and pulsed mode, in which a single control rod (named transient rod) is quickly withdrawn from the core, increasing reactivity and leading to a prompt supercritical state, which causes an exponential increase in power and temperature. However, due to the negative temperature coefficient of reactivity of the fuel used to feed the reactor, the power reaches a peak, and it rapidly decreases until shutting down fission reactions, in a process that is inherently safe. The pulses that are generated during reactor operations can have its parameters described by mathematical models, such as Fuchs-Nordheim modelling, that equate the behavior of reactivity, power and temperature during the lifespan of the pulse. However, the current model has some basic limitations, mainly because it considers that parameters such as heat capacity remain constant during the whole process, and it is known that, in practical cases of nuclear reactor operations, heat capacity is a parameter that is a function of temperature. Therefore, this article aims to evaluate the impact that the introduction of heat capacity as a linear function of temperature has on final results, comparing data with and without this assumption.
This paper describes the requirements and implementation of the Traceability System at Sirius, the Brazilian synchrotron light source. The system was designed to ensure that only personnel trained by the Radiation Protection Group operate the beamlines. The solution utilizes radio-frequency identification technology to enable the "Search" procedure, a mandatory safety step for the release of synchrotron radiation. The system integrates Siemens programmable logic controllers (PLCs), C# development for data encoding, and a web infrastructure based on MariaDB, Node-RED, and PHP for real-time monitoring. Results indicate that, between June 15, 2023 and October 24, 2025, 34,099 search procedures were performed across the 15 beamlines in operation and commissioning, involving more than 200 internal and external users. This work elucidates the system's technical architecture and demonstrates its effectiveness in radiological safety management and the traceability of experimental activities at Sirius.
Small Modular Reactors (SMRs) represent a promising technological innovation for energy transition, offering enhanced safety, operational flexibility, and modularity. This study examines critical success factors for SMR implementation in Brazil’s energy matrix, addressing regulatory, economic, technical, and social dimensions. A qualitative approach combined bibliometric analysis of 190 documents from Scopus with semi-structured interviews of nine Brazilian experts with over 15 years of experience. Results reveal regulatory framework inadequacy was identified by 77.8% of experts as the primary barrier, followed by capacity building needs (55.6%), risk management challenges (55.6%), and economic viability concerns (44.4%). Private sector participation (66.7%) and diverse industrial applications (33.3%) emerged as key opportunities. SMRs can contribute to decarbonization goals and energy security in Brazil, particularly for industrial applications in petrochemical facilities, mining operations, and offshore platforms. Successful implementation requires: (1) continuous state nuclear policy; (2) SMR-specific regulatory frameworks; (3) public-private partnership models; (4) capacity building programs; and (5) transparent communication strategies. This research provides empirical evidence from Brazilian experts and specific recommendations for policymakers, regulators, and industry stakeholders.
Computed tomography (CT) provides rapid, high-resolution 3D imaging, reducing motion artifacts and the need for sedation in pediatric patients. However, children are highly sensitive to ionizing radiation due to their developing tissues and longer life expectancy. This study proposed local diagnostic reference levels (LDRLs)) for pediatric head CT examinations at a South African (SA) tertiary hospital. A retrospective review was conducted for pediatric head CT dose length product (DLP) and volume computed tomography dose index (CTDIvol) data acquired between January 2023 and March 2024. Examinations were stratified into four age groups: <1 year, 1 – <5 years, 5 – < 10 years, and 10 – 15 years. For each group, median DLP and CTDIvol values were calculated as LDRLs and then compared with international values. Proposed LDRLs in terms of DLP (mGy.cm) were 242.6; 405.5;715.5 and 899.3 while in terms of CTDIvol (mGy) were: 13.8; 15.8; 26.0 and 38.7 respectively for <1 year; 1 – <5 years; 5 – <10 years and 10 – 15 years age groups. The DLP for SA (242.6) exceeded Brazilian (143.8) but was lower than Nigerian (1040.0) for <1-year group. For 1 – <5 years, the DLP for SA (405.5) was lower than Nigerian (988.0), yet higher than Iranian (216.9). For 5 – <10-year group, the DLP for SA (715.5) exceeded Iranian (232.8) but remained lower than Nigerian (1493.0). For 10 – 15-year group, the DLP for SA (899.3) surpassed Omani (391.0) and Brazilain (531.7) but remained lower than Nigeriain (1824.0). In case of CTDIvol (mGy) for <1-year group, SA (13.8) value exceeded Brazilian (8.8) and Omani (13.0) values. For 1 – <5 years, SA (15.8) value remained lower than Saudi Arabian (22.0) value. For 5 – < 10 years, the SA (26.0) value exceeded the Omani (19.0) value but remained lower than Saudi Arabian (29.0). For the 10 – 15 years the SA (38.7) value exceeded the Brazilian (26.9) and Omani (21.0) values but remained lower than the Irish (52.1) value. Pediatric CT doses at the proposed South African tertiary hospital fall within global ranges. However, higher values in the <1, 5 – <10, and 10 – 15-year groups compared to some international values indicate room for possible optimization.
Prolonged indoor exposure to radiation presents a public health concern, primarily due to building materials containing significant concentrations of natural radionuclides. This study was initiated in response to a documented case of elevated indoor gamma radiation in the Liwale District. The research aims to assess natural radioactivity levels in building materials sourced from this district, which is characterized by Hypoluvic Arenosols and Profondic/Arenic Luvisols derived from continental Neogene sandstone deposits, and to evaluate their potential radiological hazards. The radionuclide levels in 25 samples comprising sand, clay, and gravel were analyzed using a gamma-ray spectrometer coupled with a high-purity germanium (HPGe) detector. The average activity concentrations of 226Ra, 232Th, and 40K were 40.8±2.5 Bq kg-1, 114.9±4.1 Bq kg-1, and 311.9±14.5 Bq kg-1, respectively; Whilst 40K levels were typical, the values for 226Ra and 232Th exceeded the UNSCEAR world averages. Moreover, average values for radiological hazard indices were: Raeq, 229.1±9.6 Bq kg-1; Hex, 0.6; I, 0.8, and Eff, 0.5 mSv y-1. Notably, the average values of all indices were within their internationally recommended limits, indicating a low overall radiological risk. Nevertheless, 20% of the samples (5 out of 25) exceeded the safety thresholds for Raeq, Hex, and I, whilst 16% (4 out of 25) surpassed the limit for Eff. This signifies potential lithogenic hazards associated with the use of these building materials. Therefore, this study strongly recommends implementing stringent regulatory screening and control measures for local building materials sourced from these specific geological formations.
Gamma spectroscopy is a non-destructive technique for identifying and quantifying radionuclides in environmental samples. High-purity germanium (HPGe) detectors are commonly used for these analyses. To minimize background radiation from sources other than the sample, the detector is housed in a lead shield. ORTEC’s low-background shield, weighing approximately 1180 kg, poses challenges for automation, making such systems rare and commercially expensive. Additionally, HPGe detectors require cooling to cryogenic temperatures, typically achieved using liquid nitrogen (LN2). The drawbacks of LN2 include its high cost and the limited duration of a 30 L LN2 charge (around 14 days), regardless of detector operation. An autosampler, an automated sample-handling system, optimizes LN2 usage by enabling sample changes during idle periods. In this work, we developed a cost-effective and efficient autosampler incorporating a “pick and place” robot and a pneumatic circuit for sample manipulation, linear actuators for automated door operation, and an electronic system integrated with “Maestro” (ORTEC’s spectroscopy software) via a custom-developed Python interface. This system integrates mechanical design, electronics, and programming to enhance efficiency, optimize LN2 usage and reduce downtime, thereby improving overall operational performance.
The increasing incidence of cancer and rapid advancements in radiotherapy technology have significantly heightened the complexity of treatment processes, necessitating robust infrastructure and safety protocols. This study assessed the implementation of risk analysis methodologies in Brazilian radiotherapy facilities through a nationwide survey of 196 centers, with 111 responses (57%). Results show that the Radiotherapy Risk Assessment System (SEVRRA) is the predominant tool, applied in 86.5% of facilities, while Failure Mode and Effects Analysis (FMEA) remains limited (7.2%), with only a small fraction using both. Adoption has been uneven across regions, with the South and Southeast concentrating the majority of facilities, technological resources, and advanced treatment techniques such as IMRT, VMAT, and SRS, while the North and Central-West report fewer centers and less diversity in methodologies. The peak in implementation occurred between 2017 and 2021, particularly in 2019, influenced by regulatory standards and international recommendations. Medical physicists (69.4%) and Radiation Protection Supervisors (27.9%) are the primary professionals responsible for applying risk analysis, though regulatory compliance issues persist. Despite barriers such as workload constraints and limited training, the integration of risk analysis practices has strengthened safety protocols and quality management, underscoring their importance in minimizing risks and safeguarding patient well-being throughout radiotherapy treatment in Brazil.
Microreactors, with their compact design, high efficiency, and robust operational characteristics, represent a promising solution for clean and reliable energy generation, particularly in remote regions or emergency scenarios. A key aspect of the development of these systems is the diversification of nuclear fuels beyond conventional uranium dioxide, aimed at enhancing fuel-cycle efficiency, reducing radioactive waste, and mitigating nuclear proliferation risks. This work presents the conceptual design of a microreactor core using MOX fuel without uranium enrichment. Several initial compositions of PuO₂ + UO₂ were evaluated, and the mixture that yielded the best performance, discussed throughout the article, was 15% PuO₂ and 85% UO₂. This composition met all design constraints and enabled a fuel cycle of approximately 15 years, operating at microreactor power levels. The SCALE computational system was employed to define the fuel cell and to perform the core burnup calculations. The results demonstrate the feasibility of using unenriched MOX in microreactors, highlighting its potential to expand fuel-cycle flexibility and contribute to a more sustainable and diversified energy supply.
Prostate cancer remains a major public health concern in Brazil due to its high incidence and persistent regional inequalities. Early diagnosis is crucial for effective curative treatments, including radiation therapy; however, socioeconomic and geographic disparities significantly influence access to timely diagnosis and appropriate care. This study presents a descriptive analysis of prostate cancer management in Ceará, Northeastern Brazil, focusing on radiotherapy modalities and associated challenges. A retrospective review of 1,031 medical records from patients treated at the Integrated Regional Oncology Center (CRIO), in Fortaleza, between 2014 and 2023 was conducted. Data on demographic characteristics, disease staging, and treatment protocols were systematically analyzed, with emphasis on radiotherapy. Statistical analyses included Chi-square tests, Kruskal-Wallis tests, and multinomial regression to assess associations between patient characteristics, staging, and treatment decisions. Ethical approval was obtained (Protocol 4310688, Plataforma Brasil), with waiver of informed consent due to the retrospective design and use of de-identified data. The mean patient age was 71.3 years. Most patients were diagnosed with localized (Stage IIB, 36.3%) or locally advanced disease (Stage III, 23.2%), although a considerable proportion presented with Stage IV disease (16.0%). External Beam Radiotherapy (EBRT) was the predominant initial treatment (320 patients), whereas brachytherapy was used in less than 1% of cases. Geographic disparities were evident: 52.5% of patients came from Greater Fortaleza, reflecting centralization of oncology services. Educational attainment was generally low, with 21.5% illiterate and 63.5% having only elementary education, which may contribute to delayed diagnosis. A significant inverse association between age and disease stage (p<0.001) indicated that older patients were more frequently diagnosed at earlier stages, while younger patients tended to present with more advanced disease. Overall, the findings reveal systemic barriers to early detection and equitable treatment. The heavy reliance on EBRT, limited availability of brachytherapy—partly due to lack of domestic source production—and centralized oncology infrastructure highlight the need for improved regional planning, expanded radiotherapy capacity, and targeted strategies to reduce disparities within the public health system.
The sand extraction plays a crucial role in economic development and the construction industry. However, the fine waste generated during the extraction process brings environmental impacts on this activity. In order to promote the reuse of this waste, the synthesis of geopolymers was proposed. Geopolymers are a class of inorganic materials composed of aluminosilicates arranged in a three-dimensional network, originally developed by Joseph Davidovits in 1978. These are silica–alumina materials with an amorphous to semi-crystalline three-dimensional structure, obtained through alkaline activation. The raw materials used for their synthesis can consist of natural sources of aluminosilicates or by-products from industrial processes, which react through an alkaline activation route, generally using sodium or potassium hydroxide and silicate solutions as activating agents. These materials can be applied in the treatment of liquid radioactive waste through the sorption of cesium, which is commonly present in such waste. The study involved the characterization of mining waste, including quantitative (mineralogical) and qualitative (degree of amorphization) analyses, followed by the synthesis of the geopolymer. After 28 days of curing, the material was ground in a jaw mill and further reduced in a pulverizing mill. Cesium sorption tests with the prepared material were then carried out. The ground geopolymer was characterized by FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), XRF (X-ray Fluorescence), particle size analysis, and BET surface area measurement. Cesium sorption tests (using inactive CsCl) were performed using the batch equilibrium method, as described in the EPA Method 530. The results demonstrated that the grinding process was effective in adjusting grain size, enhancing the material’s surface area. Mineralogical characterization confirmed the presence of aluminosilicates such as kaolinite and muscovite, which have favorable sorption properties. Thermal analysis identified the temperature range at which the material reaches a stable chemical composition, as well as the regions associated with dehydration and dihydroxylation. The tests indicated that the geopolymer obtained from sand extraction waste showed high cesium sorption potential, as evidenced by the sorption isotherm results.
Healthcare waste (HCW) requires efficient treatment prior to final disposal to prevent the spread of pathogens and environmental contamination. Ionizing irradiation has emerged as a promising alternative to incineration; however, accurate absorbed-dose determination depends on knowledge of the material’s radiological properties. This work aims to develop a physical simulator for HCW to support dosimetric evaluation of irradiated waste, including experimental and computational validation. Data from the National Institute of Standards and Technology (NIST), along with the XCOM and ESTAR programs, were used to obtain mass energy-absorption coefficients for photons and mass stopping power for electrons in the energy range of 0.1 to 20 MeV. Two approaches were considered: a full compositional model representative of typical HCW, and a simplified model based on Polylactic Acid (PLA), containing only C, O, and H, assuming that PLA adequately reproduces the predominant elemental fraction of the waste. Dosimetric validation was performed by comparing mass attenuation coefficients (μ) and stopping power (S) between HCW and PLA. Computational simulations using PHITS evaluated the spatial dose distribution from photons and electrons. A physical simulator was subsequently manufactured by 3D printing in PLA, with a density of 0.15 g/cm³ and internal hexagonal geometry to reflect realistic waste packing characteristics. Comparisons of attenuation and stopping power coefficients showed minimal differences between HCW and PLA, demonstrating radiological equivalence. Simulations and analyses confirmed that the simulator effectively reproduces the spatial dose distribution, with good homogeneity and fidelity to real behavior. The use of PLA proved to be a practical, economical, and technically consistent solution for constructing simulators aimed at improving dosimetric processes in ionizing radiation treatment of healthcare waste, while also enabling reproducible studies with strong potential for practical application.
This work extends the application of the spectral-nodal method SDM, cf., Modified Spectral Deterministics (MSD-CN), to solve neutron shielding problems (fixed-source) in two-dimensional Cartesian rectangular geometry, considering problems with linearly anisotropic scattering in the formulation of discrete ordinates ( ), using a constant approximation for the transverse neutron leakage terms. The essence of this methodology lies in the use of the intranodal analytical solution of the neutron transport equation and an iterative process that employs the concept of spatial sweeping, like the Source Iteration method used in the fine-mesh method DD, cf., Diamond Difference, for estimating the angular neutron fluxes emerging in the spatial nodes. To validate the methodology, a numerical simulation of two model-problems was performed, where the MSD-CN was able to achieve numerical results with a small relative deviation compared to the reference method Diamond Difference alongside a performance test to compute the execution time of the algorithm. All methods were implemented in the computational language C++.
Hot cells are containment systems used in radiopharmaceutical production, designed to ensure radiation protection and product quality. Leak tightness testing is a mandatory requirement under CNEN NN 6.13 standard, as it directly impacts worker safety, environmental protection, and product integrity. This study aimed to perform a practical pressure change leak test in a hot cell used for radiopharmaceutical preparations, in accordance with applicable technical standards. The pressure change method was applied using pressures between 1.6 and 2.5 higher the working pressure for a testing time of 15 minutes. The method proved practical, requiring no highly specialized equipment, although its sensitivity to temperature highlights the importance of high-precision thermometer. Results showed that while the method is suitable for ISO 10648-2:1994 Class 2 compliance, it may not be adequate for Class 1 due to the risk of mathematically inaccurate results under temperature variations. Multiple rounds of leak detection and repair were required to achieve the required containment level. Overall, the DC, RIC, CIC, and Solid Waste chambers met Class 2 leak tightness requirements, being suitable for use in radiopharmacy facilities.
New radiotherapy techniques have been innovative in recent decades with the aim of maximizing the dose to tumor tissue and reducing the dose to healthy tissue. One of the modalities that has gained prominence, using low-energy beams, is intraoperative radiotherapy (IORT), as it is a method based on high radiation doses (10–20 Gy) administered to the tumor bed immediately after surgical excision. IORT can be achieved through treatment with low-energy X-ray beams with some devices available on the market. However, such devices provide little dosimetric information and lack a calibration protocol. According to the recently updated recommendations of the TRS 398 standard (2024), for the use of low-energy beams, the ideal is to use a parallel plate ionization chamber calibrated in terms of absorbed dose in water. Based on TRS 398, this work established a calibration protocol for parallel plate dosimeters in terms of absorbed dose in water at the Center for Ionizing Radiation Metrology (CEMRI) of the Institute for Energy and Nuclear Research (IPEN).
This study presents a comparative analysis between Monte Carlo simulations (MCNP-5) and experimental measurements of thermal neutron fluence using gold foil activation at the TNF2 irradiation facility of the Neutron Metrology Laboratory (LNMRI/IRD). The MCNP-5 model was constructed to replicate the irradiator geometry and source configuration. Gold foils, both bare and cadmium-covered, were irradiated and analyzed via gamma spectrometry to determine the induced activity of 198Au. The results of the calculated nuclear reaction rates were compared to the measured activities through C/E (Calculated/Experimental) analysis. The findings show consistent agreement within experimental uncertainty, supporting the accuracy of the MCNP model and reinforcing the role of TNF2 in the national and international metrological infrastructure for neutron dosimetry. Future developments will include improvements in flux mapping and personal dosimetry applications.
The development of tumor spheroids in co-culture with human fibroblasts represents an innovative approach to modeling the prostate cancer microenvironment and assessing radiation effects. In this study, we employed the "hanging drop" technique in conjunction with plate inversion to generate three-dimensional spheroids composed of prostate tumor cells (LNCAP cell line) co-cultivated with human fibroblasts. This approach aims to create a more representative in vivo-like tumor environment, facilitating a detailed analysis of the interactions between tumor cells and fibroblasts in 3D conditions. The formed spheroids were exposed to gamma radiation using a GammaCell 220 irradiator with Co-60, with the goal of investigating the effects of radiation on both fibroblastic and tumor cells. Gamma radiation is known to induce cell death, and this study examines how such damage impacts cellular morphology within the spheroid microenvironment.
